As previously mentioned, one of the new features of the Macintosh SE was its expansion connector, called PDS (Processor Direct Slot). This expansion connector allowed you to install expansion cards, such as accelerator and networking cards. Accelerator cards replaced the 68000 microprocessor with another more powerful CPU, usually a 68020, and frequently added more RAM, allowing you to have more than 4 MB.
The Macintosh Portable, the Macintosh SE/30, and the Macintosh IIfx also had a PDS connector. Although the PDS connector of the Macintosh Portable had the same number of contacts as the PDS slot of the Macintosh SE, it was not compatible with the connector available on the Macintosh SE. The Macintosh SE/30 and the Macintosh IIfx used a different model of the PDS connector, called PDS 68030, which was not compatible with the PDS connector available on the Macintosh SE.
To install an expansion card, you had to open the computer and remove the motherboard – a rather complicated process.
In Figure 24, you can see a Radius SE accelerator card installed on the Macintosh SE motherboard, which replaced the 68000 microprocessor with a 68020. In Figure 25, we show a different accelerator card that was available for the Macintosh SE, the Prodigy SE from Levco, which also replaced the microprocessor with a 68020 model and added 16 MB of RAM.
In Figures 26 and 27, you can see two different models of Ethernet cards.